Colorectal cancer (CRC) represents the third-leading killer amongst all cancer-related diseases in the US. While a number of biomarkers and technologies have been evaluated for the management of this disease, few have emerged for use by clinicians in battling CRC, with the predominant screening methods still consisting of monitoring blood in the stool and/or colonoscopy. In this R21 application, research will focus on developing micro-electrophoresis that can monitor the absence/presence of molecular biomarkers originating from nuclear DNA. The molecular assays to be investigated require high-resolution electrophoresis for reading out the results. DNA is typically separated by electrophoresis in a viscous sieving matrix using fused-silica capillaries or microchips ([unreadable]-CE). [unreadable]-CE is particularly attractive because it can be integrated to front-end processing steps to provide automated sample processing in a closed architecture free from contamination and envisioned for point-of-care testing. The matrix is loaded into the device using high pressure, which can be time and energy-intensive, must be reloaded between every run, and is expensive. The elimination of sieving matrices and the development of free-solution electrophoresis to sort DNA would drastically decrease the cost associated with molecular assays as well as simplify system set-up and reduce run time. Since both the charge and the friction scale linearly with chain length, the electrophoretic mobility of DNA in free-solution does not change with increased chain length. In order to run free-solution electrophoresis of DNA, the DNA must be conjugated to an uncharged perturbing entity or "drag-tag" producing Free-Solution Conjugate Electrophoresis (FSCE). In this application, FSCE with [unreadable]-CE devices that are fabricated in polymers using replication technology will be used for several different molecular assays, including Ligase Detection Reactions (LDR) for scoring the presence of known point mutations in K-ras oncogenes and an Endo V/LDR assay, a mutation scanning assay to score the presence of sporadic p53 mutations. In addition, microsatellite instability (MSI) will also be evaluated using [unreadable]-CE FSCE. MSI is undertaken using a panel of markers from nuclear DNA that are PCR amplified and analyzed via electrophoresis. Comparisons of electrophoretic mobilities of diseased tissue versus normal tissue provide an indication of MSI status and can be used as a prognosticator for determining effective therapies for treating CRC patients. [unreadable] [unreadable] [unreadable]